The potential for sequestering CO2 in the largest bituminous coal reserve in the United States (Illinois Basin) is being assessed in southeastern Illinois as part of the DOE’s Regional Sequestration Partnership program. The main objectives of this test are to determine CO2 injection rates and storage capacity. At the Tanquary site, the Springfield Coal is 7 ft thick, 900 ft deep, and has a coal gas content of 150 to 195 scf/ton (dmmf). Desorbed Springfield Coal gases (normalized air-free vol %) are 88-96% methane, 2-9% nitrogen, 1-3% CO2 and trace amounts of C2+. The carbon and hydrogen isotopes of the methane indicate primarily a biogenic origin. Results of injecting up to 600 tons of gas-phase CO2 over a period of 40-80 days are presented. Pre-injection DST’s, pressure transient analyses, and pulse tests indicate initial coal permeability averages 6 md. COMET 3 reservoir simulation was used to determine well spacing, track anticipated CO2 movement and to evaluate enhancing coalbed methane recovery potential. Based on tests and model results, one injection and three observation wells oriented relative to the cleat directions and spaced approximately 50 to 100 ft apart, were drilled, cased and perforated. Lab measurements of CH4, CO2 and N2 adsorption capacities, as well as coal shrinkage and swelling accompanying methane removal and CO2 adsorption, respectively, have been completed. In addition, changes in the mesopore and micropore characteristics (specific surface areas, volumes, and size distribution) as a result of CO2 adsorption have been analyzed in coals of varying petrographic composition.
|Original language||English (US)|
|Title of host publication||Abstracts - AAPG, Eastern Section Meeting|
|Publisher||American Association of Petroleum Geologists|
|State||Published - 2008|